Latch mechanism



May 9, 1944. H. T. SPARRow LATCH MEGHANISM Filed Oct. 2, 1942 2 Sheets-Sheet 1 l fg,

May 9, 1944. H'. T. sPARRow LATCH MECHANISM Filed 001'.. 2 1942 2 Sheets-Sheet 2 M R wm my 1r T u U H Y B ZJ 9 --.f4 j A Z am-;

5TM/WHEY Patented Moy e, 1944 'UNITED I STATES PATENT OFFICE l Laren amcnaNlsM Hubert 'r. swrow, Minneapolis, Minn., mimorto Minneapolis-Honeywell Regulator Gompany, Minneapolis, Minn., a corporation of Delaware Application october z, 1942. serial No. 460,493 2a claims. (ci. 29e-sou My invention relates to a magnetic control latch means and particularly to a type wherein a protective means is employed to cause release of the latch upon the occurrence of certain conditions in the circuit controlling the magnet.

In the practice maneuvering of an airplane in blind ying' a hood has been heretofore `used which projects over the cockpit somewhat like the -top of a baby buggy so as to close oil.' the pilots vision and thereby simulate actual conditions existing` under so-called blind flying, requiring the pilot to maneuver the plane entirely by the control indicating instrument of the plane. The hood and latch means are so arranged that the hood may be raised upon completion of the blind ying in order that normal `flight may be resumed.

An object of my invention is to provide a latch mechanism particularly adapted for locking the hood or an airplane in down position during the practice'maneuvering of the plane inblind Another object of my invention is to provide a latch arrangement and holding electromagnet for the latch adapted to cooperate with a blind iiying hood having a tension means for said hood. The latch is arranged so as 4to release the hood under the tension means upon a break in the circuit of the magnet due to accidentv or other cause, such as the opening of the circuit by a suitable air speed control switch such as shown in the application of Willis H. Gille, Serial No. 460,522, and dated October 2, 1942.

Another object of my invention is to provide a` latch means including a, safety featurer whereby' the latching member willnot latch by the mere accidental actuation thereof, but will rather require that the same be actuated by the latch pin or bar of the hood in the specific manner intended. y

Another object of my invention is to provide a novel switch control member mounted within a latch member and arranged so as to effect the energizatio'n of a magnet for holding the latch in a latched position upon the joint actuation of the latch and switch control member by the latch pin and to embody such perfected feature in a simple and compact form of construction.,

Another object of my invention is to provide a slidable latch member and a single spring l arrangement for holding the latch member and.

circuit of a holding magnet so as to cause the release-of the blind flying hood under suitable tension means.

A further object of my invention is to provide a slidable latch member having locking lingers actuated upon movement of the latch member so as to pivot the ilngers to a locking position and a magnet for holding the latch member and locking fingers in said locked position.

Another object of my invention is to provide a compact latch meansof great eillciency in comparison to its size and of such simplicity in construction as to adapt it for manufacture and installation at low cost and a latch mechanism adapted for use wherever a latch means may be employed.

Other objects and advantages of this inveno tion are set forth in the following description, taken with the accompanying drawings, andthe novel features thereof are pointed out in the appended claims. illustrative only and I may make changes in details, especially in matters of shape, size and arrangement of parts within the principles of .the invention, to the full extent indicated by the broad and general meanings of the terms in which the appended claims are expressed.

In theV accompanying drawings, wherein like reference characters indicate corresponding parts in the various iigures, Y v

Figure 1 is a top plan view of a latch mecha# nism embodying my present invention with the latch mechanism in locked position;

Figure 2 is a sectional view taken along the line 2-2 of Figure 1 and looking in the direction of the arrows;

Figure 3 is a similar view tothat of Figure 2 illustrating the latch mechanism in an open position; l

Figure 4 is a sectional view taken along the lines 4-4 of Figure 2 and looking in the direction of the arrows; l

switch control member simultaneously 'under spring tension.

Another object of my invention is to provide a v novel manually operable -means for opening the Figue 5 is a fragmentary sectional plan view of the electromagnet -control switch actuating mechanism and illustrates theposition assumed by the switch operating rod when unactuated by the latch bar, upon the latch mechanism being moved to the locked position such asshown in Figure 2, but without the latch bar being positioned in the said latch mechanism. and

Figure 6 is a diagrammatic view illustrating one application of my invention as applied in locking the flying hood of an airplane in lowered position. Y

Referring now to the drawings, an electromag- The disclosure, however, is

net I having a core I8 is mountedon a U-shaped housingmember2,asshowninl"igures2and3.

Insulation members 3 and 4 are mounted on opposite sides of the U-shaped housing member 2 as shown in Figure 4. One terminal of the electromagnet I is connected by an electrical conductor l to an input terminal .l as shown in Figures l and 4. The opposite terminal of the electromagnet I is connected by a conductor 1 to an arm 8 having mounted thereon a mutable control switchcontact 3l.Y Contact 8| is adapted to be engaged by a contact 82 mounted on a movable spring switch arm 9 which is fastened at one end by a bolt 33 to a bracket I3 connecting the Switch arm 9 to an electrical current input terminal- I I.

Terminals II and 6 form for the electromagnet I the input terminals of a suitable source of electrical current. The switch arml is formed oi' suitable spring-like material and normally opens the circuit of the electromagnet I at the contacts II and82. Thearmlisactuatedtoaclosed position in a manner which will be hereinafter explained.

2,349,426 A. adapted to be received inthe slots 31 and 3l, re-v spectively, and are slidably movable therein. Blot deilning edges 99 and 9| of the slots 31 and 33.

respectively, limit the movement of the side members I1 and I8 on the plate I3 upon movement of the latch housing to a locked position. while wardly into the mouth-like indenture 28. Upon such inward movement of the latch housing I9. as

A base plate I2 is fastened bythe screws 584 l and 85 to one arm of the U-shaped housing 2. The base plate l2 has formed therein the apertures 18 whereby the latch mechanism may be conveniently vmounted by suitable attachment screws or bolts. A'guide or actuating plate I3 is fastened by bolts I4 and Il to the opposite Aarm of the U-shaped housing 2. Slidably mounted between the base plate I2 and the guide plate I3 is a latch housing 'or carriage I3, as best shown inFigures 1,-2and3. I

'I'he .latch housing I8 includes opposite side plates I1 and I8 connected by the member I9. Anti-friction bearings 2l and 2I are rotatably mounted on pins and 31,' respectively. between the side plates I1 and I8. Theanti-friction bearing 29 is pomtioned so as to move along the base plate I2 while the anti-friction bearing 2| is poshown by Figure .2. the plate I3 will force 'the latch teeth 39 and 3 I downward and hold the same in a downward pivoted position locking the latch pin 29 in the mouth-like indenture 29 until the latch housing returns to the former outward or open position causing thereby the release of the latch means 39 and 3| by the plate l3-so as ,to permit the upward pivotal movement of the teeth 30 and 3| under tension of Spring 34. The electromagnet I previously described is provided for holding through the amature 22 the latch housing I6 in the inward or locked position and thereby locking the latch pin 29 in the mouthlike indenture ze by the teeth n and sl..

'I'he energization' of the electromagnet I i5 controlled through the switch arm 9 which in turn is under the control of an operating rod 39. The

operating rod 89 has a push button 49 positioned sitioned so asl to -move along the underside of A guide plate I3, thereby assuring the slidablemovement ot the latch .housing It with minimum frlctional loss. A

An armature 22 is pivotally connected by brackets 23 and 24 to the opposite sides I1 and I8 of the latch housing I8 through respective pins 28. The armature 22 cooperates with the electromagnet I in a manner which will be explained. Formed in the side members I1 and I8 of the latch housing I8 is a mouth-like indenture 29 having upper and lower jaws 21 and 28, respectively. The mouth-like indenture 23 is for receiving a latch bar or pin 29,. as will hereinafter appear.

Pivotally mounted in the upper jaw 21 of the latch housin I6 are. a pair of latch teeth or nngers 39 an 3i, which are connected by the .connecting plate member 32. The latch teeth 39 and 3I are pivotally connected to the side members I1 and I9 of the latch housing I9 by a pin 33. Surrounding the pin 33 is a spring member 34 having an end 38 connected to the latch teeth at the connecting plate 32 and an opposite end 36 secured in the member I8. The spring 34 tends to rotate the latch teeth or lingers 39 and 3i around the pivot 38 in a clockwise direction as shown in Figures 2 and 3 and thereby Itends to hold the latch teeth under spring tension out oi the mouth-like indenture 29.

Slots 3] and 38 are formed in the side members I'I and I8. respectively, of the latch housing I9. Further formed on the plate I3 are laterally at one end thereof in the latch housing I8 adjacent to the mouth-like indenture 26, as shown inFiguresl,2and3.

Fixedly connected to the armature 22 is a. tubular member 4I which is slidably disposed in the core 99 of the electromagnet I. Slidably disposed in vturn within-@the tubular member 4I is the switch operating rod 39. Disposed-intermediate 'the opposite ends of the operating rod 39 is a projecting part 42. A shoulder 'I5 is provided in the tubular member 4I adapted to engage the projecting part 42 when the operating rod 39 is moved outwardly in relation to the magnetic core 80. The projecting part 42 however disengages the shoulder 15 of the tubular member 4I when moved in the opposite relative direction, or when-the rod 39 is moved inwardly with respect to the magnetic core 89. A spring member 431s adapted to hold the operating rod 39 in engaging relation with the tubular member 4I sothat in normal operation the spring 43 holds the operating rod 39, the amature 22 and the latch housing I8 inv an outward position under to be movedoutwardly upon the extreme inward by energizing the electromagnet I.

projecting end portions 88 and 39 which are 'I6 movement of the operating rod 39. Upon such outward actuation oi' the button 44 the spring switch arm 9 will in turn be actuated so as to close the switch at the contacts 8| and 82 there- However, the operating rod 39 and the tubular member 4I are so arranged that the mere inward movement of the armature 22 to the extreme position will be insuillcient to cause the operating rod 39 to actuate the stem 45 and the button 44 to cause the switch arm 9 to be actuated to a closed position as illustrated in Figure 5. In order therefore to ascuas closethcswitchatthecontactsll andl2,itis necessary not only that the latch housing or armature 22 be moved to theextreme inward position, but that the push `button 49 abo be actuated sumciently so as to cause the operating rod 39 to move an additional amount suillcient to move the button 44 so as to cause the switch arm i l to close the circuit energizing electromagnet I.

AsmaybeseenfromFlguresZ and 3,thepush button 4I is so arranged with respect to the latch housing Il and the mouthllke indenture that the same will only be actuated upon the positioning of the latch pin 29 in the mouth-like indenture 25 in the manner intended accompanied by the inward movement of the latch housing I6 causing the joint actuation of the latch fingers or teeth 39 and 3| and the switch arm 9, as previously described. It will thus be seen that I have provided a novel safety feature for preventing the accidental energization o1' the electromagnet through movement of the latch housing alone.

However, when the latch housing I 6 and operating rod 99 are actuated in the specific manner intended, it will be seen that the teeth 30 and 3| will be positioned in locking relation to the latch pin 29 and the electromagnet will in turn be energized so as to hold the armature 22 in the extreme inward position, thereby causing the holding of the teeth 30 and 3l in the locked position through the guide plate I3, as previously described.

In order to cause the deenergization of the electromagnet I and the corresponding release of the latch pin 29 by the outward movement of the latch housing I6 under the tension of the spring 43, I have provided a novel means which will now be described. Mounted at the opposite end of the base plate I2 from that of the latch housing I are the vertically projecting members 45 and 41. as shown in Figure 1. Pivotally connected to these members by the rod 48 is a U- shaped arm 49. Connected between the opposite arms of the U-shaped member 49 is a rod 50 rotatably mounted on a second rod 94. There is mounted intermediate the ends of the rod 50 a wheel-like actuating member 5| formed of suitable insulating material. 'I'he member 5I is adapted to cooperate with the spring pressed switch arm 9 so that upon the switch arm 9 being in circuit closing relation pivotal movement of the U-shaped member 49 in a counter-clockwise direction on the members 49 and 41 as shown in Figures 1, 2 and 3 will cause through the member 5I, the actuation of the arm 9 to an open.

circuit position, thereby deenergizing the electromagnet I. A suitable spring arm 52 is provided mounted on the guide plate I3 by the screws I4 and I5. The spring arm 52 is mounted so as to engage the rod 50 to bias the U-shaped member 49 and the actuating member 5I out of engagement with the spring arm switch member 9.

`Projecting from the guide plate I3 are also the arms 53 and 54 having provided the indentures 55 and 56, respectively, as shown in Figure 1 in which are disposed the opposite arms of the U- shaped member 49. The outwardly projecting edges defining the indentures 55 and 56 limit the pivotal movement of the U-shaped member 49. It will thus be seen that in normal operation spring member 52 will bias the U-shaped member 49 to a position whereby the actuating member 5I is out of engagement with the spring pressed switch arm 9.

'Ihrough the arrangement of my switch operating rod 39, I have provided novel means whereby thetensionexertedbythesprlngonthelatch mechanism may be conveiiently released upon the energisation of the electromagnetic biasing meansforholdingthelatchmechanismina closed position. Similarly, though the arrangement of my release mechanism 49 I have provided novel means for deenergising the electromagnet and permitting the rie-application of the force oi' the spring 49 to the latch mechanism for holding the latch mechanism in an open position.

AIt will further be seen in Figure 1 and in Figure 4 that a shield 51 is provided for protecting the inlet terminals II and 5. The protective shieldlike member 51 extends inwardly and has provided the bent-under ends 5l and 59, as best shown in Figure 4. The guide plate Il is provided with projecting anges Il! and 9|. which fasten securely over the bent-under end 59 of the member 51 and an end of the insulating member 3, respectively. Similarly, the base plate ,I2 has provided the projecting anges 52 and i9 which likewise fasten an end of the insulating plate 3 and the bent-under end 59 of the member 51, respectively.

From the foregoing, it will be readily seen that a very sturdy, economical and compact latch means has been provided. Further, as shown in Figure 6, there is illustrated diagrammatically the manner in which this latch means may be used as a flying hood release latch. In the structure illustrated, the flying hood would operate under a tension spring 10 which would tend t0 pull the hood upwardly under spring tension. A handle 1I is provided whereby the operator may manually pull the hood down in closed position causing the latch bar or pin 29 to engage in the mouth-like indenture 29 of my latch mechanism indicated generally by numeral 12. The latch housing I9 is thus moved downward whereupon the armature 22 is actuated by the magnet I so as to hold the latch mechanism in locked position. As shown in Figure 6, there is provided in circuit with the electromagnet I a suitable air speed switchindicated generally by the numeral 19 of a type such as disclosed in the application (2)1! Willis H. Gille, Serial No. 460,522, filed October The air speed switch 13 has one terminal thereof electrically connected through a conductor 14 to one of the input terminals 6A or II of the electromagnet I. The remaining input terminal of electromagnet I is connected through a conductor 15 to a suitable source of electrical energy indicated by the numeral 11. A conductor 19 leads from the opposite terminal of the source of electrical energy 11 to the remaining terminal of the air speed switch 13, as shown diagrammatically in Figure 6.

The air speed switch indicated generally by numeral 13 is of a type adapted to open the circuit upon a predetermined maximum and minimum air speed so as to eliminate insofar a.r possible the dangers resulting from the plane going into a dive or stalling while the hood is in the blind flying position, speed in excess of the safe maximum indicating a dive and speed below the safe minimum speed indicatin a stall.

Thus upon the opening of t e circuit for the electromagnet I upon the minimum or maximum air speed, it will be readily seen that the electromagnet I will be deenergized and the latch housing I6 moved upward under spring tension to an open position, whereupon the latch pin 29 will be released and the flying lood under tension of spring 10 returned to an open position and normal flying resumed. Also, it will be seen that should the circuit be broken through accident or from other cause or upon power failure, the electromagnet I will similarly be deenergized causing the return of the latch member to open position, whereupon the difllculty may be easily located by the pilot. Such operation will thus assure the safe operation of the plane during the llying maneuver and prevent failure of operation due -to causes out of the control of the pilot.

In the normal operation of the plane upon completion of the blind ying maneuver, the ilying hood may be released to open position by merely pivoting upwardly with the finger the U- shaped member 49 so as to position the member 5| in such a manner as to actuate the spring arm 9 so as to break the electrical contact at the contacts 8i and 82, thereby opening the electromagnetic circuit and deenergizing the magnet I to release the ying hood under tension of the spring 10. 'I'he spring 43 will on engagement of the projecting part 42 of the rod 39 with thel shoulder 15 of the tubular member 4|, upon release of the bar 29, then bias the latch mechanism i6 in an open position. While the use of my latch mechanism is illustrated in Figure 6 as applied to a ying hood having an independent biasing means or to a hood biased downwardly by apparent that my latch mechanism may be applied to an evenly balanced hood without such a blazing means or to a hood biased downwardly by a force greater than spring 43, in which case upon the independent actuation of the rod 39 by the latch bar 29 the biasing spring 43 will be disengaged from the latch means I6. Further, it will be obvious the latch mechanism is readily adaptable for use with or without the air speed switch indicated by numeral 13. Moreover, my latch mechanism is readily .applicable for use wherever a latch means may be employed.

Further, it will be readily understood that minor changes in the size, form and construction oi the various parts of my invention may be made and substituted for those herein shown and described, without departing from the spirit of my invention, the scope oi which is set forth in the appended claims.

I claim as my invention:

l. A device of the character described, comprising, in combination, a latch means, an electromagnet for holding the latch means in locked position, control means mounted within the latch means for controlling the energization of the electromagnet and a latch bar for simultaneously actuating the latch means and the control means in such a manner as to cause the energization of the electromagnet for holding the latch means in locked position.

2. A device of the character` described, comprising in combination, a latch means, independent means for holding the latchmeans in locked position, means mounted within the latch means for controlling the actuation of the independent holding means, and means for simultaneously actuating the latch means and the independent holding means in such a manner as to hold the latch means in locked position.

3. A device of the character described, comlatch housingirom the ilrst to the second position, a control rod slidably mounted within the latch housing and one end of the control rod positioned adjacent to the said mouth-like indenture, avspring tension switch, a push button for actuating the switch, the control rod adapted to actuate the push button up'on the control rod being moved from a firstposition to a second position, an electromagnet controlled by the said switch, an armature mounted on the latch houslng for cooperation with the electromagnet, a projecting member mounted on the control rod /and adapted to engage the said armature upon prising in combination, a latch housing movable mouth-like indenture upon movement ofv the the control rod being moved to the said nrst position, a spring member biasing the said control rod to the first position in such a manner as te hold the latch housing and the control rod under spring tension in the said rst position, a latch bar for engagement in the said mouth-like indenture of the latch housing and the latch bar adapted to move the latch housing and the control rod from a iirst position to a second position whereupon the latch bar is locked in the said mouth-like indenture of the latch housing by the teeth-like members and the electromagnet is energized for holding the armature and the latch housing in the said second position.

4. In a latching mechanism for latching a de- 'vice, comprising, in combination, latch means movable from an open to a closed position, electromagnetic means for holding the latch means in a closed position, the latch means actuated from an open to a closed position by the device to be latched, switch means for controlling the energization of the electromagnetic means, and control means for closing the said switch means, the control means arranged in such a manner as to be actuated by the device to be latched upon said device actuating the latch means from an open to a closed position and thereby causing the energization of the electromagneticl means so as to hold the latch means in closed position locking the device to be latched in the latch means.

5. A device of the character described, comprising, in combination,. latch means movable from an open to a closed position, electromagnetic means for holding the latch means in4 a closed position, an electric circuit for energizing the electromagnetic means, push button means mounted within the latch means for closingthe circuit to energize the electromagnetic means and the said push button means so arranged in the said latch means as to close the circuit upon simultaneous actuation of the push button means and the latch means to a closed position.

6. In a latching mechanism for latching a device, in combination, a supporting structure. latching means carried thereby and movable to a latching position, and means for holding said latching means in its latched position including a member freely movable in reverse directions and which must be moved to and held in a predetermined position to render said holding means 1 eective, said member being spaced from said latching means, when the latching means is in latching position, by an amount which requires that the device to be latched actually be in piace and latched thereby in order for said holding means to be moved to andheld in its latch holding position. l

7. In a latching mechanism for latching a device, latching means movable to latching position, and holding means for holding said latching means in latching position and including a member which must be moved to a new position in a direction commensurate with the movement of said latching means in latching direction and held in said new position to maintain said latching means in latching position, said member being spaced from said latching means when the latching device is in its latching position whereby said member is not moved to and held in its new position by said latching means unless the device to be latched is in place.

8. In a latching mechanism for latching a device having a given configuration, in combination, latching means movable to latching position, and means to hold said latching means in latching position' including a member which must be moved to and held in a new position to rende'r said holding means eilective, said member being spaced from said latching means at all times but at a smaller distance when said latching means is in latched position than when it is in unlatched posigo tion whereby said member will be moved to and held in said new position upon movement of said iatching means to latching position only if the device to be latched is in place.

9. A device of the character described, comprising, in combination, a latch member, a support. a tubular member attached to the latch member and slida-bly mounted within the support, a push rod slidably mounted within the tubular member and positioned within the latch member, a projecting member mounted on the push rod, a shoulder portion provided on the tubular member to releasably engage the projecting member, spring means acting upon the push rod so as to hold the push rod and tubular member in releasable engaging relation for biasing the latch member to an open position, and means for actuating the push rod in suchl a manner as to disengage the pushrod from the tubular member so as to release the tension of the spring means from the latch member.

10. A device of the character described, comprising, in combination, latch means, rst biasing means for forcing the latch means to an open position, second biasing means for holding the latch means in a closed position, and control means for alternatively applying the forces of the aforesaid biasing means to the latch means.

` 11. A' device of the character described, comprising, in combination, latch means, spring means for holding the latch means in an open position, electromagnetic means for holding the latch means in a closed position, and manually operable control means for disengaging the spring means and energizing the electromagnetic means.

12. A devicey of the character described comprising, in combination, latch means, springv means for holding the latch means in an open .f. position, electromagnetic means for holding the latch means in a closed position, and manually operable control means for deenergizing the electromagnetic means and engaging the spring means with the said latch means.

13. A device of the character described, comprising, in combination. latch means,l ilrst biasing means for forcing the latch means to an open position, second biasing means for forcing the latch means to a closed position, first control means for applying to the latch means the force of the second biasing means and releasing the force of the rst biasing means, and second control means for applying to the latch means the force of the'ilrst biasing means and releasing the force of the secondbiasing means.

14. In a latching mechanism for latching a 7l combination. latch means.

device, comprising. in

an electromagnet for holding the latch means ina closed position. a tubular member attached to the latch means and slidably mounted within the electromagnet, a push rod slidably mounted within the tubular member and having one end positioned within the latch means, a projecting part mounted on the push rod, a shoulder portion provided on the tubular member to releasably engage the projecting part.. spring means acting upon the push rod so as to hold the push rod and tubular member in releasable engaging relation for biasing the latch member to an open position, switch means for controlling the energization of the electromagnet, the said latch means actuated by the device to be latched to a closed position and the said push rod simultaneously actuated by the device to be latched in such a manner as to cause the push rod to disengage the tubular member causing the actuation of the said switch means so as to energize the electromagnet for holding the latch means in a closed position. 15. In a latching mechanism for latching a device, comprising, in combination, latch means, an electromagnet for holding the latch means in a closed position, a tubular member attached to the latch means and slidably mounted within the electromagnet, a push rod slidably mounted within the tubular member and having one end positioned within the latch means, a projecting part `mounted on the push rod, a shoulder portion provided on the tubular member to releasably engage the projecting part, spring means acting upon the push rod so as to hold the push rod and tubular member in releasable'engaging relation for biasing the latch member to an open position, switch means for controlling the energization of the electromagnet, the said latch means actuated by the device to be latched to a closed position together with said push rod in such a manner as to disengage the tubular member causing the actuation of the said switch means so as to energize the electromagnet for holding the latch means in a closed position, a pivotally mounted lever, a roller mounted on the said lever for actuating the switch means so as to deenergize the said electromagnet whereupon the push rod is returned to engaging relation with the tubular member aforesaid under tension of the spring means whereby the latch means is A biased to an open position.

16. A device of the character described, comprising, in combination, a supporting member, a guide member, a latch carriage slidably mounted between the supporting member and the guide member, the said latch carriage movable from a first position to a second position, the latch carriage having formed therein a mouth-like indenture, a locking linger pivotally connected to the latch carriage, the said locking finger slidably actuated by the guide member whereby uponllmovement of the latch carriage from the nrst'tb the second position movement is imparted by the guide member to the locking linger moving the said nnger into the mouth-like indenture in a locking position, magnetic means for holding the latch carriage in the said second position whereupon the guide member is adapted to secure the locking nnger in the aforesaid locking position.

17. A device of the character described, comprising, in combination, a supporting member, an actuating member, a latch housing slidably mounted between the supporting member and the actuating member, the said latch housing movable from a first position to a second position, the latch housinghaving formed therein a mouth-like indenture, locking fingers pivotally connected to the latch housing and movable in and out of the said mouth-like indenture, spring means biasing the locking iingers out of the said mouth-like indenture, the actuating member forcing the locking fingers into the said mouthlike indenture upon movement of the latch housing from the first pdsition to the second position, electromagnetic means for holding the latch housing in the said second position. means for controlling the energization of the said electromagnetic means, and guard means for permitting in normal operation the actuation of the said control means to energize the said electromagnetic means only upon movement of the latch housing' to the second position.

18. A latching mechanism for latching a device, comprising, in combination, a latch member, an electromagnet for releasably holding the latch member in a locked relationship to the device to be latched, control means for causing the energization of the electromagnet, the control means arranged so as to be actuated by the device to be latched upon movement of said device in the latch member.

19. A latching mechanism for latching a device, comprising, in combination a latch member slidably movable from an -open to a closed position', an electromagnet for holding the latch member in the closed position, control means for energizing the electromagnet and adapted to be actuated by the device to be latched upon movement of the latch member io a closed position, and manually operable means for actuating the control means to deenergizing the electromagnet.

20. In a latching mechanism for latching a device having a given conguration, in combination, a latching means movable to latching position, a switch means, a circuit, electromagnet means to hold said latching means in latching position, land means for operating the switch means including a member which must be lmoved to and held in a new position to actuate the switch means to close its circuit to render said holding means effective, said member being spaced from said latching means at all times but at a smaller distance when said latching means is in latching position than when said latching means is in unlatched position wfnereby said member will be moved to and held in said new position upon movement of said latching means to latching position only if the device to be latched isin place. i.

21. In a latching mechanism for latching a device having a given configuration, in combination, latching means movable to latching position, electromagnet means 'to hold said latchlng means in latching position including a member which must be moved to and held in a new pol sition to render said electromagnet holding means eifective, saidgmember being spaced from said latching means at all times but at a smaller distance when said latching means is in latched position than when it is in unlatched position l whereby said member will be moved to and held in said new position upon movement ofsaid latching means to latching position only if the device to be latched is in place.

22. In a. latching mechanism for latching a device, in combination, a supporting structure,

latching means carried 'thereby and movable to a latching position, electromagnet means for holding said latching means in its latched position including a member freely movable in reverse direction and which must be moved to and $0 amount which requires that the device held in a predetermined position to render said electromagnet holding means eective, said member lbeing spaced lfrom said latching means, when thelatching means is in latching position, by an to be latched actually be in place and latched thereby in order for said holding means to be moved to and held in its latch holding position.

23. In a latching mechanism for latching a device, in combination, a supporting structure,

latching means carried thereby and movable to a latching position, a switch`means, a circuit, and electromagnet means for holding said latching means in its latching position, and means for actuating said switch means including a member freely movable in reverse direction and which must be moved to and held in a predetermined position to actuate the switch means to close the circuit to render said electromagnet holding means effective, said member being spaced from the latching means, when the latching means is in latching position, by an amount which requires that the deviceto be latched actually .be in place and latched in order for said holding means to be moved to and held in its latch holding position.

. HUBERT T. SPARROW.

Patent' No. 2,5u8,l26.

CERTIFICATE 'oF CORRECTION.

' nay* 9a; 19M-l. HUBERT T.' srmow.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page h, first column, line 28, for "or to ahood biased downwardly by read the spring y 70, it will be readilp--gline 51, for "biazing" read biasing-w; and that Y the said Letters Patent should be [read with this correction therein thatl the'same may conforxxto the record of the case in the'Patent Office.

signed and sealed this 12th day of september, A. D. 191m.

Leslie Frazer 

